The damage of aluminum castings mainly occurs on the surface, and the surface strengthening of aluminum alloys has important economic value. The corrosion resistance of cast aluminum alloy is improved by electrochemical methods, such as micro arc oxidation, electrodeposition, multi arc ion plating, chemical composite plating and chemical conversion film. aluminum alloy cast can be modified by electrochemical method. The purpose is to endow the surface with corrosion resistance, wear resistance, decoration and other properties.

  Microarcoxidation (MAO), also known as microplasma oxidation (Microplasmaoxidation, MPO), is a combination of the electrolyte and the corresponding electrical parameters. The surface of aluminum, magnesium, titanium and its alloys depends on the transient high temperature and pressure generated by arc discharge, and the ceramic coating is mainly composed of matrix metal oxide. Due to the simultaneous existence of chemical oxidation, electrochemical oxidation and plasma oxidation in the process of micro arc oxidation, micro arc oxidation process introduced the working area into the high voltage discharge region, which greatly improved the comprehensive performance of the film. The micro arc oxidation coating is firmly bonded to the substrate, compact in structure and high in toughness. It has good wear resistance, corrosion resistance, high temperature impact resistance and electrical insulation. The technology is simple and easy to adjust the function of the film, and the process is not complicated. It does not cause environmental pollution. It is a new green and environment-friendly material surface treatment technology. It has a broad application prospect in aerospace, machinery, electronics, decoration and other fields.

Alloying elements Cu and Mg are beneficial to micro arc oxidation, while Si is hindered by micro arc oxidation. Hou Zhaohui et al. [1] studied the micro arc oxidation process conditions, film structure and film formation process of ZL series cast aluminum alloy with silicon content of 8% to 12%. The results show that the ceramic oxide film is fine, uniform, thick and microhardness, and the micro arc oxidation of the cast aluminum alloy can be carried out smoothly in the electrolyte system of micro arc oxidation, and the Na2WO4 and EDTA two sodium can improve the hardness of the film. The conditions of obtaining ZL109 alloy micro arc oxidation film under study conditions are NaOH:2 ~ 4g/L, water glass: 5 ~ 7mL/L, Na2WO4:2 to 4g/L, EDTA two sodium: 2 ~ 4g/L, the current density of micro arc oxidation 30 ~ 40A/dm2, solution temperature 30~40 degrees, and strong stirring. In addition, the micro arc oxidation of ZL109 was studied by Gong Jianfei and other [2]. The thickness of the dense layer was 76&mu, and the microhardness was more than m, and the microhardness of HV1600 was uniformly oxidized to ceramic coating.

ADC12 die casting aluminum alloy is widely used in piston, belt wheel and other components and structural parts such as automobiles, motorcycles and instruments. Zhang Jinbin and other [3] studies the influence of electrolyte composition and electrical parameters on the coating properties of black ceramic film prepared by Microplasma Oxidation on ADC12 aluminum alloy surface. The results show that the concentration of sodium phosphate is low, the surface is rough, the concentration is too high and the concentration is 12 to 15g/L, the optimum concentration is gold and the gold in the additive M1 and M2 components. The larger the proportion of the element oxide K in the film, the higher the black saturation of the film is, the best concentration is 10 to 11.0g/L and 15 to 18.0g/L, the best pH value of the film is 8 ~ 9, and the optimum current density of the saturated dark black is 3 to 4.0A/dm2, and the best electrolyte formula is used to make black. The film thickness is 20 ~ 30μ m, hardness HV500 ~ 700, black saturation 0.8 ~ 1.

The damage of aluminum castings mainly occurs on the surface, and the surface strengthening of aluminum alloys has important economic value. The corrosion resistance of cast aluminum alloy is improved by electrochemical methods, such as micro arc oxidation, electrodeposition, multi arc ion plating, chemical composite plating and chemical conversion film. The casting aluminum alloy can be obtained by electrochemical method. The purpose is to give the surface corrosion resistance, wear resistance, decoration and other characteristics.